Reasons for ink caking and ink stacking
ink stacking is directly related to ink caking, which can cause ink gelatinization and vitrification of printing ink film. An appropriate increase in pH value or the selection of cheap inorganic salts can restore the original printability of ink, which can not only improve the fluidity and washability, but also reduce the resulting foam or gelation. In this regard, the author analyzes the following main reasons from the above phenomenon
1. The addition of white carbon black can overcome the stratification of ink and prevent the precipitation of ink, but excessive addition will lead to the immobility of ink and the reduction of the gloss of printing ink film
2. Although the relative density of pigments or fillers is the same, but the particle core size is not equal, they will also be in a flocculation state
3. The ink will flocculate or gelatinize after the invasion of acidic substances
4. The solvent volatilization gradient in the ink body is not good. The experimental machine of Jinan new era Gold Testing Instrument Co., Ltd. is of good quality, low price, and can be solved in 24 hours after sales. In particular, the proportion of true solvent and co solvent is unbalanced, and the release (exothermic) or volatilization of neutralizer and co neutralizer is unbalanced
5. When ammonia is added into the absorbed carbon dioxide, the electrification of particles is blocked, the oxidation is accelerated, and the combination of oxygen molecules in water is promoted. At the same time, excessive addition will also affect the gloss
6. After the ink comes into contact with the air, there is an oxide film mixed into the ink and the ink may have precipitated particles or short inkiness and uneven dispersion
7. The resin monomer composition is small, especially the acrylic resin. When the acrylic system also provides customers with complete engineering support, the monomer of enoic acid will disappear when it increases to 30%
8. So that the experiment can work normally. Too strong ink absorption, agglomeration and uneven dispersion will cause poor ink transmission
9. Excessive dispersion
10. Due to improper storage, the ink absorbs moisture, resulting in flocculation
11. The ink is mixed with paper scraps or fabric scraps
12. Misuse of solvents. For example, some amphoteric solvents or active solvent molecules associate to form rubber size aggregates
13. The ink yield value is too high, the ink head is too short, the pigment content is too high, especially the filler is not alkali resistant binder, which leads to its expansion. If Shanghai self-adhesive printing adopts acid solvent, it will be reduced to solid state, and then dissolved with solvent
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